This invention relates to electric power storage, through power interface electronics and electromechanical energy conversion, in the inertia of a spinning flywheel, and by reciprocal means, stored kinetic energy conversion to electric power. The various component elements of the invention include: A high-speed motor/generator, with cooperative power electronics and magnetic bearings, electronic feedback control servos to stabilize the magnetic bearings, a vertical-axis flywheel, integral with the motor/generator rotor and rotatable magnetic bearing elements, to store kinetic energy, a vacuum enclosure to reduce air drag, mechanical backup bearings that are not engaged during normal service, and a stationary energy-absorbing installation site to safely house the flywheel and its enclosure.
As also illustrated in the above-referenced United States patents, such means as rechargeable electrochemical batteries offer some usages, but encounter huge problems involving key issues such as storage space, leakage and longevity. Therefore, flywheel driven systems may offer distinct advantages over such systems. However, as flywheel power storage system designs have evolved from smaller, physically limited structures with minimal storage capacity, to the high capacity systems employing industrial sized magnetic members prevalent today, material restrictions and other such inherent factors have arisen. Said considerations must be overcome in order to facilitate reaching the maximal energy storage and output to render flywheel energy storage systems a viable alternative.
In modern applications, due to the need for extremely large magnetic arrays and magnetic members, failure of high capacity flywheel systems can be triggered by overloading and overheating of the touchdown ball bearing. When utilizing a pure electromagnet lift magnet, failure often occurs as the electrical power is tripped during normal operation due to the high lifting force requirement. As the lifting force dissipates, the heavy rotor will then sit on the ball bearings, and thus, due to the heavy load, will heat up the ball bearings in a short expanse of time. Thus, as the ball bearing fails, the high speed rotor loses the mechanical support, and rotates basically out of round, contacting the casing. Thus, wear, catastrophic at times and even explosions within the casing may occur.
Further, advanced flywheels are generally vertically mounted rotors, which are levitated by magnetic bearing systems, ether active or passive. These systems can be prone to failure due to power outage or overheating and during this type of event, the entire weight of the rotor may crash down upon and subsequently rests upon a mechanical backup bearing. Obviously, designing backup bearing systems to rectify these problems arising from power failure and/or overheating has become more challenging as flywheels become larger and operate at high speeds. Various types of mechanical bearings have been considered, designed and tested, but the extreme loads involved invariably cause the bearing to overheat, resulting in a very short life cycle and catastrophic failure.
What is needed is a backup bearing system which allows rotating systems to acquire and maintain high speeds and a high energy flywheel. What is additionally needed is a backup bearing system which can handle the full weight of the rotor upon failure, for an extended period so that no secondary damage occurs if there is a failure of the primary magnetic lift bearing.
Additionally, what is needed is a system, mechanism or method of operation, which minimizes the load on the ball bearings in the case where the rotor drops on the bearing for any potential failure mode.